[media] xc5000: Split config and set code for analog/radio

As we need a function that reapply the last tuned radio,
in order to do resume, split the code that validates and
updates the internal priv struct from the ones that
actually set radio and TV.

A latter patch will add support for resume.

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>